Merge pull request #9627 from yyforyongyu/sweep-under-budget

Sweep inputs even the budget cannot be covered

docs/release-notes/release-notes-0.19.0.md

@@ -162,6 +162,12 @@ close transaction.
   tests to set a lower value for faster funding confirmation timeout while
   keeping the default of 2016 blocks for production stability.
 
+* Previously when sweeping inputs, the sweeper will wait until the specified
+  budget can be covered by the inputs, which could cause the sweep to be
+  delayed, and the sweeping tx ends up using large fees. This is now
+  [changed](https://github.com/lightningnetwork/lnd/pull/9627) so the sweeper
+  will always attempt the sweep as long as the budget can be partially covered.
+
 ## RPC Additions
 
 * [Add a new rpc endpoint](https://github.com/lightningnetwork/lnd/pull/8843)

itest/list_on_test.go

@@ -690,6 +690,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "rbf coop close",
 		TestFunc: testCoopCloseRbf,
 	},
+	{
+		Name:     "bump fee low budget",
+		TestFunc: testBumpFeeLowBudget,
+	},
 }
 
 // appendPrefixed is used to add a prefix to each test name in the subtests

itest/lnd_funding_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
+	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/chainreg"
 	"github.com/lightningnetwork/lnd/funding"
 	"github.com/lightningnetwork/lnd/labels"
@@ -466,20 +467,29 @@ func runChannelFundingInputTypes(ht *lntest.HarnessTest, alice,
 		burnAddr = "bcrt1qxsnqpdc842lu8c0xlllgvejt6rhy49u6fmpgyz"
 	)
 
-	fundMixed := func(amt btcutil.Amount, target *node.HarnessNode) {
+	fundMixed := func(amt btcutil.Amount,
+		target *node.HarnessNode) *wire.MsgTx {
+
 		ht.FundCoins(amt/5, target)
 		ht.FundCoins(amt/5, target)
 		ht.FundCoinsP2TR(amt/5, target)
 		ht.FundCoinsP2TR(amt/5, target)
 		ht.FundCoinsP2TR(amt/5, target)
+
+		return nil
 	}
-	fundMultipleP2TR := func(amt btcutil.Amount, target *node.HarnessNode) {
+	fundMultipleP2TR := func(amt btcutil.Amount,
+		target *node.HarnessNode) *wire.MsgTx {
+
 		ht.FundCoinsP2TR(amt/4, target)
 		ht.FundCoinsP2TR(amt/4, target)
 		ht.FundCoinsP2TR(amt/4, target)
 		ht.FundCoinsP2TR(amt/4, target)
+
+		return nil
 	}
-	fundWithTypes := []func(amt btcutil.Amount, target *node.HarnessNode){
+	fundWithTypes := []func(amt btcutil.Amount,
+		target *node.HarnessNode) *wire.MsgTx{
 		ht.FundCoins, ht.FundCoinsNP2WKH, ht.FundCoinsP2TR, fundMixed,
 		fundMultipleP2TR,
 	}

itest/lnd_multi-hop_force_close_test.go

@@ -2570,7 +2570,7 @@ func runLocalPreimageClaimLeased(ht *lntest.HarnessTest,
 	// We'll now mine enough blocks so Carol decides that she needs to go
 	// on-chain to claim the HTLC as Bob has been inactive.
 	numBlocks := padCLTV(
-		invoiceExpiry - ht.CurrentHeight() - incomingBroadcastDelta - 1,
+		invoiceExpiry - ht.CurrentHeight() - incomingBroadcastDelta,
 	)
 	ht.MineBlocks(int(numBlocks))
 

itest/lnd_sweep_test.go

@@ -1606,40 +1606,62 @@ func runBumpFee(ht *lntest.HarnessTest, alice *node.HarnessNode) {
 	assertPendingSweepResp := func(broadcastAttempts uint32, budget uint64,
 		deadline uint32, startingFeeRate uint64) *wire.MsgTx {
 
-		// Alice should still have one pending sweep.
-		pendingSweep := ht.AssertNumPendingSweeps(alice, 1)[0]
+		err := wait.NoError(func() error {
+			// Alice should still have one pending sweep.
+			ps := ht.AssertNumPendingSweeps(alice, 1)[0]
 
-		// Validate all fields returned from `PendingSweeps` are as
-		// expected.
-		require.Equal(ht, op.TxidBytes, pendingSweep.Outpoint.TxidBytes)
-		require.Equal(ht, op.OutputIndex,
-			pendingSweep.Outpoint.OutputIndex)
-		require.Equal(ht, walletrpc.WitnessType_TAPROOT_PUB_KEY_SPEND,
-			pendingSweep.WitnessType)
-		require.EqualValuesf(ht, value, pendingSweep.AmountSat,
-			"amount not matched: want=%d, got=%d", value,
-			pendingSweep.AmountSat)
-		require.True(ht, pendingSweep.Immediate)
+			// Validate all fields returned from `PendingSweeps` are
+			// as expected.
+			//
+			// These fields should stay the same during the test so
+			// we assert the values without wait.
+			require.Equal(ht, op.TxidBytes, ps.Outpoint.TxidBytes)
+			require.Equal(ht, op.OutputIndex,
+				ps.Outpoint.OutputIndex)
+			require.Equal(ht,
+				walletrpc.WitnessType_TAPROOT_PUB_KEY_SPEND,
+				ps.WitnessType)
+			require.EqualValuesf(ht, value, ps.AmountSat,
+				"amount not matched: want=%d, got=%d", value,
+				ps.AmountSat)
 
-		require.Equal(ht, broadcastAttempts,
-			pendingSweep.BroadcastAttempts)
-		require.EqualValuesf(ht, budget, pendingSweep.Budget,
-			"budget not matched: want=%d, got=%d", budget,
-			pendingSweep.Budget)
+			// The following fields can change during the test so we
+			// return an error if they don't match, which will be
+			// checked again in this wait call.
+			if ps.Immediate != true {
+				return fmt.Errorf("Immediate should be true")
+			}
 
-		// Since the request doesn't specify a deadline, we expect the
-		// existing deadline to be used.
-		require.Equalf(ht, deadline, pendingSweep.DeadlineHeight,
-			"deadline height not matched: want=%d, got=%d",
-			deadline, pendingSweep.DeadlineHeight)
+			if broadcastAttempts != ps.BroadcastAttempts {
+				return fmt.Errorf("broadcastAttempts not "+
+					"matched: want=%d, got=%d",
+					broadcastAttempts, ps.BroadcastAttempts)
+			}
+			if budget != ps.Budget {
+				return fmt.Errorf("budget not matched: "+
+					"want=%d, got=%d", budget, ps.Budget)
+			}
 
-		// Since the request specifies a starting fee rate, we expect
-		// that to be used as the starting fee rate.
-		require.Equalf(ht, startingFeeRate,
-			pendingSweep.RequestedSatPerVbyte, "requested "+
-				"starting fee rate not matched: want=%d, "+
-				"got=%d", startingFeeRate,
-			pendingSweep.RequestedSatPerVbyte)
+			// Since the request doesn't specify a deadline, we
+			// expect the existing deadline to be used.
+			if deadline != ps.DeadlineHeight {
+				return fmt.Errorf("deadline height not "+
+					"matched: want=%d, got=%d", deadline,
+					ps.DeadlineHeight)
+			}
+
+			// Since the request specifies a starting fee rate, we
+			// expect that to be used as the starting fee rate.
+			if startingFeeRate != ps.RequestedSatPerVbyte {
+				return fmt.Errorf("requested starting fee "+
+					"rate not matched: want=%d, got=%d",
+					startingFeeRate,
+					ps.RequestedSatPerVbyte)
+			}
+
+			return nil
+		}, wait.DefaultTimeout)
+		require.NoError(ht, err, "timeout checking pending sweep")
 
 		// We expect to see Alice's original tx and her CPFP tx in the
 		// mempool.
@@ -1879,7 +1901,7 @@ func runBumpFee(ht *lntest.HarnessTest, alice *node.HarnessNode) {
 	// Finally, we test the behavior of lowering the fee rate. The fee func
 	// that has,
 	// - starting fee rate: 1 sat/vbyte.
-	// - deadline: 1008.
+	// - deadline: 1.
 	// - budget: 1000 sats.
 	bumpFeeReq = &walletrpc.BumpFeeRequest{
 		Outpoint: op,
@@ -1888,22 +1910,45 @@ func runBumpFee(ht *lntest.HarnessTest, alice *node.HarnessNode) {
 		SatPerVbyte: startFeeRate,
 		// The budget and the deadline delta must be set together.
 		Budget:        smallBudget,
-		DeadlineDelta: uint32(sweep.DefaultDeadlineDelta),
+		DeadlineDelta: 1,
 	}
 	alice.RPC.BumpFee(bumpFeeReq)
 
+	// Calculate the ending fee rate, which is used in the above fee bump
+	// when fee function's max posistion is reached.
+	txWeight := ht.CalculateTxWeight(sweepTx6)
+	endingFeeRate := chainfee.NewSatPerKWeight(
+		btcutil.Amount(smallBudget), txWeight,
+	)
+
+	// Since the fee function has been maxed out, the starting fee rate for
+	// the next sweep attempt should be the ending fee rate.
+	//
+	// TODO(yy): The weight estimator used in the sweeper gives a different
+	// result than the weight calculated here, which is the result from
+	// `blockchain.GetTransactionWeight`. For this particular tx:
+	// - result from the `weightEstimator`: 445 wu
+	// - result from `GetTransactionWeight`: 444 wu
+	//
+	// This means the fee rates are different,
+	// - `weightEstimator`: 2247 sat/kw, or 8 sat/vb (8.988 round down)
+	// - here we have 2252 sat/kw, or 9 sat/vb (9.008 round down)
+	//
+	// We should investigate and check whether if it's possible to make the
+	// `weightEstimator` more accurate.
+	expectedStartFeeRate := uint64(endingFeeRate.FeePerVByte()) - 1
+
 	// Assert the pending sweep is created with the expected values:
 	// - broadcast attempts: 7.
-	// - starting fee rate: 1 sat/vbyte.
-	// - deadline: 1008.
+	// - starting fee rate: 8 sat/vbyte.
+	// - deadline: 1.
 	// - budget: 1000 sats.
 	sweepTx7 := assertPendingSweepResp(
-		7, smallBudget, deadline, startFeeRate,
+		7, smallBudget, uint32(currentHeight+1), expectedStartFeeRate,
 	)
 
 	// Since this budget is too small to cover the RBF, we expect the
 	// sweeping attempt to fail.
-	//
 	require.Equal(ht, sweepTx6.TxHash(), sweepTx7.TxHash(), "tx6 should "+
 		"not be replaced: tx6=%v, tx7=%v", sweepTx6.TxHash(),
 		sweepTx7.TxHash())
@@ -1912,7 +1957,7 @@ func runBumpFee(ht *lntest.HarnessTest, alice *node.HarnessNode) {
 	// initial broadcast always succeeds.
 	assertFeeRateGreater(testFeeRate)
 
-	// Clean up the mempol.
+	// Clean up the mempool.
 	ht.MineBlocksAndAssertNumTxes(1, 2)
 }
 
@@ -2328,6 +2373,181 @@ func testFeeReplacement(ht *lntest.HarnessTest) {
 		uint64(feeRate), 0.02, "want %d, got %d in tx=%v",
 		currentFeeRate, feeRate, outgoingSweep2.TxHash())
 
-	// Finally, clean the mempol.
+	// Finally, clean the mempool.
 	ht.MineBlocksAndAssertNumTxes(1, 1)
 }
+
+// testBumpFeeLowBudget checks that when the requested ideal budget cannot be
+// met, the sweeper still sweeps the input with the actual budget.
+func testBumpFeeLowBudget(ht *lntest.HarnessTest) {
+	// Create a new node with a large `maxfeerate` so it's easier to run the
+	// test.
+	alice := ht.NewNode("Alice", []string{
+		"--sweeper.maxfeerate=10000",
+	})
+
+	// Fund Alice 2 UTXOs, each has 100k sats. One of the UTXOs will be used
+	// to create a tx which she sends some coins to herself. The other will
+	// be used as the budget when CPFPing the above tx.
+	coin := btcutil.Amount(100_000)
+	ht.FundCoins(coin, alice)
+	ht.FundCoins(coin, alice)
+
+	// Alice sends 50k sats to herself.
+	tx := ht.SendCoins(alice, alice, coin/2)
+	txid := tx.TxHash()
+
+	// Get Alice's wallet balance to calculate the fees used in the above
+	// tx.
+	resp := alice.RPC.WalletBalance()
+
+	// balance is the expected final balance. Alice's initial balance is
+	// 200k sats, with 100k sats as the budget for the sweeping tx, which
+	// means her final balance should be 100k sats minus the mining fees
+	// used in the above `SendCoins`.
+	balance := btcutil.Amount(
+		resp.UnconfirmedBalance + resp.ConfirmedBalance,
+	)
+	fee := coin*2 - balance
+	ht.Logf("Alice's expected final balance=%v, fee=%v", balance, fee)
+
+	// Alice now tries to bump the first output on this tx.
+	op := &lnrpc.OutPoint{
+		TxidBytes:   txid[:],
+		OutputIndex: uint32(0),
+	}
+	value := btcutil.Amount(tx.TxOut[0].Value)
+
+	// assertPendingSweepResp is a helper closure that asserts the response
+	// from `PendingSweep` RPC is returned with expected values. It also
+	// returns the sweeping tx for further checks.
+	assertPendingSweepResp := func(budget uint64,
+		deadline uint32) *wire.MsgTx {
+
+		// Alice should still have one pending sweep.
+		pendingSweep := ht.AssertNumPendingSweeps(alice, 1)[0]
+
+		// Validate all fields returned from `PendingSweeps` are as
+		// expected.
+		require.Equal(ht, op.TxidBytes, pendingSweep.Outpoint.TxidBytes)
+		require.Equal(ht, op.OutputIndex,
+			pendingSweep.Outpoint.OutputIndex)
+		require.Equal(ht, walletrpc.WitnessType_TAPROOT_PUB_KEY_SPEND,
+			pendingSweep.WitnessType)
+		require.EqualValuesf(ht, value, pendingSweep.AmountSat,
+			"amount not matched: want=%d, got=%d", value,
+			pendingSweep.AmountSat)
+		require.True(ht, pendingSweep.Immediate)
+
+		require.EqualValuesf(ht, budget, pendingSweep.Budget,
+			"budget not matched: want=%d, got=%d", budget,
+			pendingSweep.Budget)
+
+		// Since the request doesn't specify a deadline, we expect the
+		// existing deadline to be used.
+		require.Equalf(ht, deadline, pendingSweep.DeadlineHeight,
+			"deadline height not matched: want=%d, got=%d",
+			deadline, pendingSweep.DeadlineHeight)
+
+		// We expect to see Alice's original tx and her CPFP tx in the
+		// mempool.
+		txns := ht.GetNumTxsFromMempool(2)
+
+		// Find the sweeping tx - assume it's the first item, if it has
+		// the same txid as the parent tx, use the second item.
+		sweepTx := txns[0]
+		if sweepTx.TxHash() == tx.TxHash() {
+			sweepTx = txns[1]
+		}
+
+		return sweepTx
+	}
+
+	// Use a budget that Alice cannot cover using her wallet UTXOs.
+	budget := coin * 2
+
+	// Use a deadlineDelta of 3 such that the fee func is initialized as,
+	// - starting fee rate: 1 sat/vbyte
+	// - deadline: 3
+	// - budget: 200% of Alice's available funds.
+	deadlineDelta := 3
+
+	// First bump request - we expect it to succeed as Alice's current funds
+	// can cover the fees used here given the position of the fee func is at
+	// 0.
+	bumpFeeReq := &walletrpc.BumpFeeRequest{
+		Outpoint:      op,
+		Budget:        uint64(budget),
+		Immediate:     true,
+		DeadlineDelta: uint32(deadlineDelta),
+	}
+	alice.RPC.BumpFee(bumpFeeReq)
+
+	// Calculate the deadline height.
+	deadline := ht.CurrentHeight() + uint32(deadlineDelta)
+
+	// Assert the pending sweep is created with the expected values:
+	// - deadline: 3+current height.
+	// - budget: 2x the wallet balance.
+	sweepTx1 := assertPendingSweepResp(uint64(budget), deadline)
+
+	// Mine a block to trigger Alice's sweeper to fee bump the tx.
+	//
+	// Second bump request - we expect it to succeed as Alice's current
+	// funds can cover the fees used here, which is 66.7% of her available
+	// funds given the position of the fee func is at 1.
+	ht.MineEmptyBlocks(1)
+
+	// Assert the old sweeping tx has been replaced.
+	ht.AssertTxNotInMempool(sweepTx1.TxHash())
+
+	// Assert a new sweeping tx is made.
+	sweepTx2 := assertPendingSweepResp(uint64(budget), deadline)
+
+	// Mine a block to trigger Alice's sweeper to fee bump the tx.
+	//
+	// Third bump request - we expect it to fail as Alice's current funds
+	// cannot cover the fees now, which is 133.3% of her available funds
+	// given the position of the fee func is at 2.
+	ht.MineEmptyBlocks(1)
+
+	// Assert the above sweeping tx is still in the mempool.
+	ht.AssertTxInMempool(sweepTx2.TxHash())
+
+	// Fund Alice 200k sats, which will be used to cover the budget.
+	//
+	// TODO(yy): We are funding Alice more than enough - at this stage Alice
+	// has a confirmed UTXO of `coin` amount in her wallet, so ideally we
+	// should only fund another UTXO of `coin` amount. However, since the
+	// confirmed wallet UTXO has already been used in sweepTx2, there's no
+	// easy way to tell her wallet to reuse that UTXO in the upcoming
+	// sweeping tx.
+	// To properly fix it, we should provide more granular UTXO management
+	// here by leveraing `LeaseOutput` - whenever we use a wallet UTXO, we
+	// should lock it first. And when the sweeping attempt fails, we should
+	// release it so the UTXO can be used again in another batch.
+	walletTx := ht.FundCoinsUnconfirmed(coin*2, alice)
+
+	// Mine a block to confirm the above funding coin.
+	//
+	// Fourth bump request - we expect it to succeed as Alice's current
+	// funds can cover the full budget.
+	ht.MineBlockWithTx(walletTx)
+
+	flakeRaceInBitcoinClientNotifications(ht)
+
+	// Assert Alice's previous sweeping tx has been replaced.
+	ht.AssertTxNotInMempool(sweepTx2.TxHash())
+
+	// Assert the pending sweep is created with the expected values:
+	// - deadline: 3+current height.
+	// - budget: 2x the wallet balance.
+	sweepTx3 := assertPendingSweepResp(uint64(budget), deadline)
+	require.NotEqual(ht, sweepTx2.TxHash(), sweepTx3.TxHash())
+
+	// Mine the sweeping tx.
+	ht.MineBlocksAndAssertNumTxes(1, 2)
+
+	// Assert Alice's wallet balance.       a
+	ht.WaitForBalanceConfirmed(alice, balance)
+}

lntest/harness.go

@@ -2,7 +2,6 @@ package lntest
 
 import (
 	"context"
-	"encoding/hex"
 	"fmt"
 	"strings"
 	"testing"
@@ -1425,7 +1424,7 @@ func (h *HarnessTest) IsNeutrinoBackend() bool {
 // transaction that pays to the target should confirm. For neutrino backend,
 // the `confirmed` param is ignored.
 func (h *HarnessTest) fundCoins(amt btcutil.Amount, target *node.HarnessNode,
-	addrType lnrpc.AddressType, confirmed bool) {
+	addrType lnrpc.AddressType, confirmed bool) *wire.MsgTx {
 
 	initialBalance := target.RPC.WalletBalance()
 
@@ -1443,25 +1442,14 @@ func (h *HarnessTest) fundCoins(amt btcutil.Amount, target *node.HarnessNode,
 		PkScript: addrScript,
 		Value:    int64(amt),
 	}
-	h.miner.SendOutput(output, defaultMinerFeeRate)
+	txid := h.miner.SendOutput(output, defaultMinerFeeRate)
 
-	// Encode the pkScript in hex as this the format that it will be
-	// returned via rpc.
-	expPkScriptStr := hex.EncodeToString(addrScript)
+	// Get the funding tx.
+	tx := h.GetRawTransaction(*txid)
+	msgTx := tx.MsgTx()
 
-	// Now, wait for ListUnspent to show the unconfirmed transaction
-	// containing the correct pkscript.
-	//
 	// Since neutrino doesn't support unconfirmed outputs, skip this check.
 	if !h.IsNeutrinoBackend() {
-		utxos := h.AssertNumUTXOsUnconfirmed(target, 1)
-
-		// Assert that the lone unconfirmed utxo contains the same
-		// pkscript as the output generated above.
-		pkScriptStr := utxos[0].PkScript
-		require.Equal(h, pkScriptStr, expPkScriptStr,
-			"pkscript mismatch")
-
 		expectedBalance := btcutil.Amount(
 			initialBalance.UnconfirmedBalance,
 		) + amt
@@ -1472,48 +1460,56 @@ func (h *HarnessTest) fundCoins(amt btcutil.Amount, target *node.HarnessNode,
 	// the target node's unconfirmed balance reflects the expected balance
 	// and exit.
 	if !confirmed {
-		return
+		return msgTx
 	}
 
 	// Otherwise, we'll generate 1 new blocks to ensure the output gains a
 	// sufficient number of confirmations and wait for the balance to
 	// reflect what's expected.
-	h.MineBlocksAndAssertNumTxes(1, 1)
+	h.MineBlockWithTx(msgTx)
 
 	expectedBalance := btcutil.Amount(initialBalance.ConfirmedBalance) + amt
 	h.WaitForBalanceConfirmed(target, expectedBalance)
+
+	return msgTx
 }
 
 // FundCoins attempts to send amt satoshis from the internal mining node to the
 // targeted lightning node using a P2WKH address. 1 blocks are mined after in
 // order to confirm the transaction.
-func (h *HarnessTest) FundCoins(amt btcutil.Amount, hn *node.HarnessNode) {
-	h.fundCoins(amt, hn, lnrpc.AddressType_WITNESS_PUBKEY_HASH, true)
+func (h *HarnessTest) FundCoins(amt btcutil.Amount,
+	hn *node.HarnessNode) *wire.MsgTx {
+
+	return h.fundCoins(amt, hn, lnrpc.AddressType_WITNESS_PUBKEY_HASH, true)
 }
 
 // FundCoinsUnconfirmed attempts to send amt satoshis from the internal mining
 // node to the targeted lightning node using a P2WKH address. No blocks are
 // mined after and the UTXOs are unconfirmed.
 func (h *HarnessTest) FundCoinsUnconfirmed(amt btcutil.Amount,
-	hn *node.HarnessNode) {
+	hn *node.HarnessNode) *wire.MsgTx {
 
-	h.fundCoins(amt, hn, lnrpc.AddressType_WITNESS_PUBKEY_HASH, false)
+	return h.fundCoins(
+		amt, hn, lnrpc.AddressType_WITNESS_PUBKEY_HASH, false,
+	)
 }
 
 // FundCoinsNP2WKH attempts to send amt satoshis from the internal mining node
 // to the targeted lightning node using a NP2WKH address.
 func (h *HarnessTest) FundCoinsNP2WKH(amt btcutil.Amount,
-	target *node.HarnessNode) {
+	target *node.HarnessNode) *wire.MsgTx {
 
-	h.fundCoins(amt, target, lnrpc.AddressType_NESTED_PUBKEY_HASH, true)
+	return h.fundCoins(
+		amt, target, lnrpc.AddressType_NESTED_PUBKEY_HASH, true,
+	)
 }
 
 // FundCoinsP2TR attempts to send amt satoshis from the internal mining node to
 // the targeted lightning node using a P2TR address.
 func (h *HarnessTest) FundCoinsP2TR(amt btcutil.Amount,
-	target *node.HarnessNode) {
+	target *node.HarnessNode) *wire.MsgTx {
 
-	h.fundCoins(amt, target, lnrpc.AddressType_TAPROOT_PUBKEY, true)
+	return h.fundCoins(amt, target, lnrpc.AddressType_TAPROOT_PUBKEY, true)
 }
 
 // FundNumCoins attempts to send the given number of UTXOs from the internal

lntest/harness_miner.go

@@ -247,7 +247,15 @@ func (h *HarnessTest) GetBestBlock() (*chainhash.Hash, int32) {
 
 // MineBlockWithTx mines a single block to include the specifies tx only.
 func (h *HarnessTest) MineBlockWithTx(tx *wire.MsgTx) *wire.MsgBlock {
-	return h.miner.MineBlockWithTx(tx)
+	// Update the harness's current height.
+	defer h.updateCurrentHeight()
+
+	block := h.miner.MineBlockWithTx(tx)
+
+	// Finally, make sure all the active nodes are synced.
+	h.AssertActiveNodesSyncedTo(block.BlockHash())
+
+	return block
 }
 
 // ConnectToMiner connects the miner to a temp miner.

rpcserver.go

@@ -4841,12 +4841,17 @@ func createRPCOpenChannel(r *rpcServer, dbChannel *channeldb.OpenChannel,
 		)
 	}
 
-	// Create a set of the HTLCs found in the remote commitment, which is
+	// Create two sets of the HTLCs found in the remote commitment, which is
 	// used to decide whether the HTLCs from the local commitment has been
 	// locked in or not.
-	remoteHTLCs := fn.NewSet[[32]byte]()
+	remoteIncomingHTLCs := fn.NewSet[uint64]()
+	remoteOutgoingHTLCs := fn.NewSet[uint64]()
 	for _, htlc := range dbChannel.RemoteCommitment.Htlcs {
-		remoteHTLCs.Add(htlc.RHash)
+		if htlc.Incoming {
+			remoteIncomingHTLCs.Add(htlc.HtlcIndex)
+		} else {
+			remoteOutgoingHTLCs.Add(htlc.HtlcIndex)
+		}
 	}
 
 	for i, htlc := range localCommit.Htlcs {
@@ -4855,7 +4860,10 @@ func createRPCOpenChannel(r *rpcServer, dbChannel *channeldb.OpenChannel,
 
 		circuitMap := r.server.htlcSwitch.CircuitLookup()
 
-		var forwardingChannel, forwardingHtlcIndex uint64
+		var (
+			forwardingChannel, forwardingHtlcIndex uint64
+			lockedIn                               bool
+		)
 		switch {
 		case htlc.Incoming:
 			circuit := circuitMap.LookupCircuit(
@@ -4871,6 +4879,8 @@ func createRPCOpenChannel(r *rpcServer, dbChannel *channeldb.OpenChannel,
 				forwardingHtlcIndex = circuit.Outgoing.HtlcID
 			}
 
+			lockedIn = remoteIncomingHTLCs.Contains(htlc.HtlcIndex)
+
 		case !htlc.Incoming:
 			circuit := circuitMap.LookupOpenCircuit(
 				htlcswitch.CircuitKey{
@@ -4890,6 +4900,8 @@ func createRPCOpenChannel(r *rpcServer, dbChannel *channeldb.OpenChannel,
 
 				forwardingHtlcIndex = circuit.Incoming.HtlcID
 			}
+
+			lockedIn = remoteOutgoingHTLCs.Contains(htlc.HtlcIndex)
 		}
 
 		channel.PendingHtlcs[i] = &lnrpc.HTLC{
@@ -4900,7 +4912,7 @@ func createRPCOpenChannel(r *rpcServer, dbChannel *channeldb.OpenChannel,
 			HtlcIndex:           htlc.HtlcIndex,
 			ForwardingChannel:   forwardingChannel,
 			ForwardingHtlcIndex: forwardingHtlcIndex,
-			LockedIn:            remoteHTLCs.Contains(rHash),
+			LockedIn:            lockedIn,
 		}
 
 		// Add the Pending Htlc Amount to UnsettledBalance field.
@@ -9056,6 +9068,9 @@ func (r *rpcServer) getChainSyncInfo() (*chainSyncInfo, error) {
 
 	// Exit early if the wallet is not synced.
 	if !isSynced {
+		rpcsLog.Debugf("Wallet is not synced to height %v yet",
+			bestHeight)
+
 		return info, nil
 	}
 
@@ -9074,6 +9089,9 @@ func (r *rpcServer) getChainSyncInfo() (*chainSyncInfo, error) {
 
 	// Exit early if the channel graph is not synced.
 	if !isSynced {
+		rpcsLog.Debugf("Graph is not synced to height %v yet",
+			bestHeight)
+
 		return info, nil
 	}
 
@@ -9084,5 +9102,10 @@ func (r *rpcServer) getChainSyncInfo() (*chainSyncInfo, error) {
 	// Overwrite isSynced and return.
 	info.isSynced = height == bestHeight
 
+	if !info.isSynced {
+		rpcsLog.Debugf("Blockbeat is not synced to height %v yet",
+			bestHeight)
+	}
+
 	return info, nil
 }

sweep/fee_bumper.go

@@ -1103,17 +1103,36 @@ func (t *TxPublisher) handleInitialTxError(r *monitorRecord, err error) {
 	case errors.Is(err, ErrTxNoOutput):
 		result.Event = TxFailed
 
-	// When the error is due to budget being used up, we'll send a TxFailed
-	// so these inputs can be retried with a different group in the next
-	// block.
-	case errors.Is(err, ErrMaxPosition):
-		result.Event = TxFailed
-
 	// When the error is due to zero fee rate delta, we'll send a TxFailed
 	// so these inputs can be retried in the next block.
 	case errors.Is(err, ErrZeroFeeRateDelta):
 		result.Event = TxFailed
 
+	// When the error is due to budget being used up, we'll send a TxFailed
+	// so these inputs can be retried with a different group in the next
+	// block.
+	case errors.Is(err, ErrMaxPosition):
+		fallthrough
+
+	// If the tx doesn't not have enough budget, or if the inputs amounts
+	// are not sufficient to cover the budget, we will return a TxFailed
+	// event so the sweeper can handle it by re-clustering the utxos.
+	case errors.Is(err, ErrNotEnoughInputs),
+		errors.Is(err, ErrNotEnoughBudget):
+
+		result.Event = TxFailed
+
+		// Calculate the starting fee rate to be used when retry
+		// sweeping these inputs.
+		feeRate, err := t.calculateRetryFeeRate(r)
+		if err != nil {
+			result.Event = TxFatal
+			result.Err = err
+		}
+
+		// Attach the new fee rate.
+		result.FeeRate = feeRate
+
 	// When there are missing inputs, we'll create a TxUnknownSpend bump
 	// result here so the rest of the inputs can be retried.
 	case errors.Is(err, ErrInputMissing):
@@ -1259,56 +1278,17 @@ func (t *TxPublisher) createUnknownSpentBumpResult(
 		SpentInputs: r.spentInputs,
 	}
 
-	// Get the fee function, which will be used to decided the next fee rate
-	// to use if the sweeper decides to retry sweeping this input.
-	feeFunc := r.feeFunction
-
-	// When the record is failed before the initial broadcast is attempted,
-	// it will have a nil fee func. In this case, we'll create the fee func
-	// here.
-	//
-	// NOTE: Since the current record is failed and will be deleted, we
-	// don't need to update the record on this fee function. We only need
-	// the fee rate data so the sweeper can pick up where we left off.
-	if feeFunc == nil {
-		f, err := t.initializeFeeFunction(r.req)
-		// TODO(yy): The only error we would receive here is when the
-		// pkScript is not recognized by the weightEstimator. What we
-		// should do instead is to check the pkScript immediately after
-		// receiving a sweep request so we don't need to check it again,
-		// which will also save us from error checking from several
-		// callsites.
-		if err != nil {
-			log.Errorf("Failed to create fee func for record %v: "+
-				"%v", r.requestID, err)
-
-			// Overwrite the event and error so the sweeper will
-			// remove this input.
-			result.Event = TxFatal
-			result.Err = err
-
-			return result
-		}
-
-		feeFunc = f
-	}
-
-	// Since the sweeping tx has been replaced by another party's tx, we
-	// missed this block window to increase its fee rate. To make sure the
-	// fee rate stays in the initial line, we now ask the fee function to
-	// give us the next fee rate as if the sweeping tx were RBFed. This new
-	// fee rate will be used as the starting fee rate if the upper system
-	// decides to continue sweeping the rest of the inputs.
-	_, err := feeFunc.Increment()
+	// Calculate the next fee rate for the retry.
+	feeRate, err := t.calculateRetryFeeRate(r)
 	if err != nil {
-		// The fee function has reached its max position - nothing we
-		// can do here other than letting the user increase the budget.
-		log.Errorf("Failed to calculate the next fee rate for "+
-			"Record(%v): %v", r.requestID, err)
+		// Overwrite the event and error so the sweeper will
+		// remove this input.
+		result.Event = TxFatal
+		result.Err = err
 	}
 
 	// Attach the new fee rate to be used for the next sweeping attempt.
-	result.FeeRate = feeFunc.FeeRate()
+	result.FeeRate = feeRate
 
 	return result
 }
@@ -1757,9 +1737,11 @@ func prepareSweepTx(inputs []input.Input, changePkScript lnwallet.AddrWithKey,
 
 	// Make sure total output amount is less than total input amount.
 	if requiredOutput+txFee > totalInput {
-		return 0, noChange, noLocktime, fmt.Errorf("insufficient "+
-			"input to create sweep tx: input_sum=%v, "+
-			"output_sum=%v", totalInput, requiredOutput+txFee)
+		log.Errorf("Insufficient input to create sweep tx: "+
+			"input_sum=%v, output_sum=%v", totalInput,
+			requiredOutput+txFee)
+
+		return 0, noChange, noLocktime, ErrNotEnoughInputs
 	}
 
 	// The value remaining after the required output and fees is the
@@ -1861,18 +1843,33 @@ func (t *TxPublisher) handleReplacementTxError(r *monitorRecord,
 		return fn.Some(*bumpResult)
 	}
 
-	// If the error is not fee related, we will return a `TxFailed` event
-	// so this input can be retried.
+	// Return a failed event to retry the sweep.
+	event := TxFailed
+
+	// Calculate the next fee rate for the retry.
+	feeRate, ferr := t.calculateRetryFeeRate(r)
+	if ferr != nil {
+		// If there's an error with the fee calculation, we need to
+		// abort the sweep.
+		event = TxFatal
+	}
+
+	// If the error is not fee related, we will return a `TxFailed` event so
+	// this input can be retried.
 	result := fn.Some(BumpResult{
-		Event:     TxFailed,
+		Event:     event,
 		Tx:        oldTx,
 		Err:       err,
 		requestID: r.requestID,
+		FeeRate:   feeRate,
 	})
 
-	// If the tx doesn't not have enought budget, we will return a result so
+	// If the tx doesn't not have enough budget, or if the inputs amounts
+	// are not sufficient to cover the budget, we will return a result so
 	// the sweeper can handle it by re-clustering the utxos.
-	if errors.Is(err, ErrNotEnoughBudget) {
+	if errors.Is(err, ErrNotEnoughBudget) ||
+		errors.Is(err, ErrNotEnoughInputs) {
+
 		log.Warnf("Fail to fee bump tx %v: %v", oldTx.TxHash(), err)
 		return result
 	}
@@ -1883,3 +1880,59 @@ func (t *TxPublisher) handleReplacementTxError(r *monitorRecord,
 
 	return result
 }
+
+// calculateRetryFeeRate calculates a new fee rate to be used as the starting
+// fee rate for the next sweep attempt if the inputs are to be retried. When the
+// fee function is nil it will be created here, and an error is returned if the
+// fee func cannot be initialized.
+func (t *TxPublisher) calculateRetryFeeRate(
+	r *monitorRecord) (chainfee.SatPerKWeight, error) {
+
+	// Get the fee function, which will be used to decided the next fee rate
+	// to use if the sweeper decides to retry sweeping this input.
+	feeFunc := r.feeFunction
+
+	// When the record is failed before the initial broadcast is attempted,
+	// it will have a nil fee func. In this case, we'll create the fee func
+	// here.
+	//
+	// NOTE: Since the current record is failed and will be deleted, we
+	// don't need to update the record on this fee function. We only need
+	// the fee rate data so the sweeper can pick up where we left off.
+	if feeFunc == nil {
+		f, err := t.initializeFeeFunction(r.req)
+
+		// TODO(yy): The only error we would receive here is when the
+		// pkScript is not recognized by the weightEstimator. What we
+		// should do instead is to check the pkScript immediately after
+		// receiving a sweep request so we don't need to check it again,
+		// which will also save us from error checking from several
+		// callsites.
+		if err != nil {
+			log.Errorf("Failed to create fee func for record %v: "+
+				"%v", r.requestID, err)
+
+			return 0, err
+		}
+
+		feeFunc = f
+	}
+
+	// Since we failed to sweep the inputs, either the sweeping tx has been
+	// replaced by another party's tx, or the current output values cannot
+	// cover the budget, we missed this block window to increase its fee
+	// rate. To make sure the fee rate stays in the initial line, we now ask
+	// the fee function to give us the next fee rate as if the sweeping tx
+	// were RBFed. This new fee rate will be used as the starting fee rate
+	// if the upper system decides to continue sweeping the rest of the
+	// inputs.
+	_, err := feeFunc.Increment()
+	if err != nil {
+		// The fee function has reached its max position - nothing we
+		// can do here other than letting the user increase the budget.
+		log.Errorf("Failed to calculate the next fee rate for "+
+			"Record(%v): %v", r.requestID, err)
+	}
+
+	return feeFunc.FeeRate(), nil
+}

sweep/fee_bumper_test.go

@@ -1134,6 +1134,7 @@ func TestCreateAnPublishFail(t *testing.T) {
 	// Create a test feerate and return it from the mock fee function.
 	feerate := chainfee.SatPerKWeight(1000)
 	m.feeFunc.On("FeeRate").Return(feerate)
+	m.feeFunc.On("Increment").Return(true, nil).Once()
 
 	// Create a testing monitor record.
 	req := createTestBumpRequest()

sweep/sweeper.go

@@ -951,7 +951,9 @@ func (s *UtxoSweeper) markInputsPublished(tr *TxRecord, set InputSet) error {
 }
 
 // markInputsPublishFailed marks the list of inputs as failed to be published.
-func (s *UtxoSweeper) markInputsPublishFailed(set InputSet) {
+func (s *UtxoSweeper) markInputsPublishFailed(set InputSet,
+	feeRate chainfee.SatPerKWeight) {
+
 	// Reschedule sweep.
 	for _, inp := range set.Inputs() {
 		op := inp.OutPoint()
@@ -978,6 +980,15 @@ func (s *UtxoSweeper) markInputsPublishFailed(set InputSet) {
 
 		// Update the input's state.
 		pi.state = PublishFailed
+
+		log.Debugf("Input(%v): updating params: starting fee rate "+
+			"[%v -> %v]", op, pi.params.StartingFeeRate,
+			feeRate)
+
+		// Update the input using the fee rate specified from the
+		// BumpResult, which should be the starting fee rate to use for
+		// the next sweeping attempt.
+		pi.params.StartingFeeRate = fn.Some(feeRate)
 	}
 }
 
@@ -1699,7 +1710,7 @@ func (s *UtxoSweeper) handleBumpEventTxFailed(resp *bumpResp) {
 	// the inputs specified by the set.
 	//
 	// TODO(yy): should we also remove the failed tx from db?
-	s.markInputsPublishFailed(resp.set)
+	s.markInputsPublishFailed(resp.set, resp.result.FeeRate)
 }
 
 // handleBumpEventTxReplaced handles the case where the sweeping tx has been
@@ -1948,7 +1959,7 @@ func (s *UtxoSweeper) handleUnknownSpendTx(inp *SweeperInput, tx *wire.MsgTx) {
 func (s *UtxoSweeper) handleBumpEventTxUnknownSpend(r *bumpResp) {
 	// Mark the inputs as publish failed, which means they will be retried
 	// later.
-	s.markInputsPublishFailed(r.set)
+	s.markInputsPublishFailed(r.set, r.result.FeeRate)
 
 	// Get all the inputs that are not spent in the current sweeping tx.
 	spentInputs := r.result.SpentInputs
@@ -1982,15 +1993,9 @@ func (s *UtxoSweeper) handleBumpEventTxUnknownSpend(r *bumpResp) {
 			continue
 		}
 
-		log.Debugf("Input(%v): updating params: starting fee rate "+
-			"[%v -> %v], immediate [%v -> true]", op,
-			input.params.StartingFeeRate, r.result.FeeRate,
-			input.params.Immediate)
+		log.Debugf("Input(%v): updating params: immediate [%v -> true]",
+			op, r.result.FeeRate, input.params.Immediate)
 
-		// Update the input using the fee rate specified from the
-		// BumpResult, which should be the starting fee rate to use for
-		// the next sweeping attempt.
-		input.params.StartingFeeRate = fn.Some(r.result.FeeRate)
 		input.params.Immediate = true
 		inputsToRetry = append(inputsToRetry, input)
 	}

sweep/sweeper_test.go

@@ -232,39 +232,51 @@ func TestMarkInputsPublishFailed(t *testing.T) {
 		inputPublishFailed, inputSwept, inputExcluded, inputFatal,
 	})
 
+	feeRate := chainfee.SatPerKWeight(1000)
+
 	// Mark the test inputs. We expect the non-exist input and the
 	// inputInit to be skipped, and the final input to be marked as
 	// published.
-	s.markInputsPublishFailed(set)
+	s.markInputsPublishFailed(set, feeRate)
 
 	// We expect unchanged number of pending inputs.
 	require.Len(s.inputs, 7)
 
 	// We expect the init input's state to stay unchanged.
-	require.Equal(Init,
-		s.inputs[inputInit.OutPoint()].state)
+	pi := s.inputs[inputInit.OutPoint()]
+	require.Equal(Init, pi.state)
+	require.True(pi.params.StartingFeeRate.IsNone())
 
 	// We expect the pending-publish input's is now marked as publish
 	// failed.
-	require.Equal(PublishFailed,
-		s.inputs[inputPendingPublish.OutPoint()].state)
+	pi = s.inputs[inputPendingPublish.OutPoint()]
+	require.Equal(PublishFailed, pi.state)
+	require.Equal(feeRate, pi.params.StartingFeeRate.UnsafeFromSome())
 
 	// We expect the published input's is now marked as publish failed.
-	require.Equal(PublishFailed,
-		s.inputs[inputPublished.OutPoint()].state)
+	pi = s.inputs[inputPublished.OutPoint()]
+	require.Equal(PublishFailed, pi.state)
+	require.Equal(feeRate, pi.params.StartingFeeRate.UnsafeFromSome())
 
 	// We expect the publish failed input to stay unchanged.
-	require.Equal(PublishFailed,
-		s.inputs[inputPublishFailed.OutPoint()].state)
+	pi = s.inputs[inputPublishFailed.OutPoint()]
+	require.Equal(PublishFailed, pi.state)
+	require.True(pi.params.StartingFeeRate.IsNone())
 
 	// We expect the swept input to stay unchanged.
-	require.Equal(Swept, s.inputs[inputSwept.OutPoint()].state)
+	pi = s.inputs[inputSwept.OutPoint()]
+	require.Equal(Swept, pi.state)
+	require.True(pi.params.StartingFeeRate.IsNone())
 
 	// We expect the excluded input to stay unchanged.
-	require.Equal(Excluded, s.inputs[inputExcluded.OutPoint()].state)
+	pi = s.inputs[inputExcluded.OutPoint()]
+	require.Equal(Excluded, pi.state)
+	require.True(pi.params.StartingFeeRate.IsNone())
 
-	// We expect the failed input to stay unchanged.
-	require.Equal(Fatal, s.inputs[inputFatal.OutPoint()].state)
+	// We expect the fatal input to stay unchanged.
+	pi = s.inputs[inputFatal.OutPoint()]
+	require.Equal(Fatal, pi.state)
+	require.True(pi.params.StartingFeeRate.IsNone())
 
 	// Assert mocked statements are executed as expected.
 	mockStore.AssertExpectations(t)

sweep/tx_input_set.go

@@ -244,6 +244,28 @@ func (b *BudgetInputSet) addInput(input SweeperInput) {
 	b.inputs = append(b.inputs, &input)
 }
 
+// addWalletInput takes a wallet UTXO and adds it as an input to be used as
+// budget for the input set.
+func (b *BudgetInputSet) addWalletInput(utxo *lnwallet.Utxo) error {
+	input, err := createWalletTxInput(utxo)
+	if err != nil {
+		return err
+	}
+
+	pi := SweeperInput{
+		Input: input,
+		params: Params{
+			DeadlineHeight: fn.Some(b.deadlineHeight),
+		},
+	}
+	b.addInput(pi)
+
+	log.Debugf("Added wallet input to input set: op=%v, amt=%v",
+		pi.OutPoint(), utxo.Value)
+
+	return nil
+}
+
 // NeedWalletInput returns true if the input set needs more wallet inputs.
 //
 // A set may need wallet inputs when it has a required output or its total
@@ -274,7 +296,9 @@ func (b *BudgetInputSet) NeedWalletInput() bool {
 		}
 
 		// Get the amount left after covering the input's own budget.
-		// This amount can then be lent to the above input.
+		// This amount can then be lent to the above input. For a wallet
+		// input, its `Budget` is set to zero, which means the whole
+		// input can be borrowed to cover the budget.
 		budget := inp.params.Budget
 		output := btcutil.Amount(inp.SignDesc().Output.Value)
 		budgetBorrowable += output - budget
@@ -296,11 +320,19 @@ func (b *BudgetInputSet) NeedWalletInput() bool {
 	return budgetBorrowable < budgetNeeded
 }
 
-// copyInputs returns a copy of the slice of the inputs in the set.
-func (b *BudgetInputSet) copyInputs() []*SweeperInput {
-	inputs := make([]*SweeperInput, len(b.inputs))
-	copy(inputs, b.inputs)
-	return inputs
+// hasNormalInput return a bool to indicate whether there exists an input that
+// doesn't require a TxOut. When an input has no required outputs, it's either a
+// wallet input, or an input we want to sweep.
+func (b *BudgetInputSet) hasNormalInput() bool {
+	for _, inp := range b.inputs {
+		if inp.RequiredTxOut() != nil {
+			continue
+		}
+
+		return true
+	}
+
+	return false
 }
 
 // AddWalletInputs adds wallet inputs to the set until the specified budget is
@@ -335,40 +367,35 @@ func (b *BudgetInputSet) AddWalletInputs(wallet Wallet) error {
 		return utxos[i].Value < utxos[j].Value
 	})
 
-	// Make a copy of the current inputs. If the wallet doesn't have enough
-	// utxos to cover the budget, we will revert the current set to its
-	// original state by removing the added wallet inputs.
-	originalInputs := b.copyInputs()
-
 	// Add wallet inputs to the set until the specified budget is covered.
 	for _, utxo := range utxos {
-		input, err := createWalletTxInput(utxo)
+		err := b.addWalletInput(utxo)
 		if err != nil {
 			return err
 		}
 
-		pi := SweeperInput{
-			Input: input,
-			params: Params{
-				DeadlineHeight: fn.Some(b.deadlineHeight),
-			},
-		}
-		b.addInput(pi)
-
-		log.Debugf("Added wallet input to input set: op=%v, amt=%v",
-			pi.OutPoint(), utxo.Value)
-
 		// Return if we've reached the minimum output amount.
 		if !b.NeedWalletInput() {
 			return nil
 		}
 	}
 
-	// The wallet doesn't have enough utxos to cover the budget. Revert the
-	// input set to its original state.
-	b.inputs = originalInputs
+	// Exit if there are no inputs can contribute to the fees.
+	if !b.hasNormalInput() {
+		return ErrNotEnoughInputs
+	}
 
-	return ErrNotEnoughInputs
+	// If there's at least one input that can contribute to fees, we allow
+	// the sweep to continue, even though the full budget can't be met.
+	// Maybe later more wallet inputs will become available and we can add
+	// them if needed.
+	budget := b.Budget()
+	total, spendable := b.inputAmts()
+	log.Warnf("Not enough wallet UTXOs: need budget=%v, has spendable=%v, "+
+		"total=%v, missing at least %v, sweeping anyway...", budget,
+		spendable, total, budget-spendable)
+
+	return nil
 }
 
 // Budget returns the total budget of the set.
@@ -404,6 +431,28 @@ func (b *BudgetInputSet) Inputs() []input.Input {
 	return inputs
 }
 
+// inputAmts returns two values for the set - the total input amount, and the
+// spendable amount. Only the spendable amount can be used to pay the fees.
+func (b *BudgetInputSet) inputAmts() (btcutil.Amount, btcutil.Amount) {
+	var (
+		totalAmt     btcutil.Amount
+		spendableAmt btcutil.Amount
+	)
+
+	for _, inp := range b.inputs {
+		output := btcutil.Amount(inp.SignDesc().Output.Value)
+		totalAmt += output
+
+		if inp.RequiredTxOut() != nil {
+			continue
+		}
+
+		spendableAmt += output
+	}
+
+	return totalAmt, spendableAmt
+}
+
 // StartingFeeRate returns the max starting fee rate found in the inputs.
 //
 // NOTE: part of the InputSet interface.

sweep/tx_input_set_test.go

@@ -133,6 +133,47 @@ func TestBudgetInputSetAddInput(t *testing.T) {
 	require.Equal(t, btcutil.Amount(200), set.Budget())
 }
 
+// TestAddWalletInput asserts `addWalletInput` successfully converts a wallet
+// UTXO into a `SweeperInput` with the correct deadline.
+func TestAddWalletInput(t *testing.T) {
+	t.Parallel()
+
+	// Create a testing deadline.
+	deadline := int32(1000)
+
+	// Initialize an empty input set.
+	set := &BudgetInputSet{
+		deadlineHeight: deadline,
+	}
+
+	// Create an utxo with unknown address type to trigger an error.
+	utxo := &lnwallet.Utxo{
+		AddressType: lnwallet.UnknownAddressType,
+	}
+
+	// Check that the error is returned from addWalletInput.
+	err := set.addWalletInput(utxo)
+	require.Error(t, err)
+
+	// Create a wallet utxo.
+	utxo = &lnwallet.Utxo{
+		AddressType: lnwallet.WitnessPubKey,
+		Value:       1000,
+	}
+
+	// Check that no error is returned from addWalletInput.
+	err = set.addWalletInput(utxo)
+	require.NoError(t, err)
+
+	// Check the input has been added to the set.
+	require.Len(t, set.inputs, 1)
+
+	// Assert the wallet input is added using the set's deadline.
+	inp := set.inputs[0]
+	require.True(t, inp.params.DeadlineHeight.IsSome())
+	require.Equal(t, deadline, inp.params.DeadlineHeight.UnsafeFromSome())
+}
+
 // TestNeedWalletInput checks that NeedWalletInput correctly determines if a
 // wallet input is needed.
 func TestNeedWalletInput(t *testing.T) {
@@ -345,12 +386,12 @@ func TestNeedWalletInput(t *testing.T) {
 	}
 }
 
-// TestAddWalletInputReturnErr tests the three possible errors returned from
+// TestAddWalletInputsReturnErr tests the three possible errors returned from
 // AddWalletInputs:
 // - error from ListUnspentWitnessFromDefaultAccount.
 // - error from createWalletTxInput.
 // - error when wallet doesn't have utxos.
-func TestAddWalletInputReturnErr(t *testing.T) {
+func TestAddWalletInputsReturnErr(t *testing.T) {
 	t.Parallel()
 
 	wallet := &MockWallet{}
@@ -395,10 +436,9 @@ func TestAddWalletInputReturnErr(t *testing.T) {
 	require.ErrorIs(t, err, ErrNotEnoughInputs)
 }
 
-// TestAddWalletInputNotEnoughInputs checks that when there are not enough
-// wallet utxos, an error is returned and the budget set is reset to its
-// initial state.
-func TestAddWalletInputNotEnoughInputs(t *testing.T) {
+// TestAddWalletInputsNotEnoughInputs checks that when there are not enough
+// wallet utxos, no error is returned as long as the wallet is not empty.
+func TestAddWalletInputsNotEnoughInputs(t *testing.T) {
 	t.Parallel()
 
 	wallet := &MockWallet{}
@@ -416,6 +456,13 @@ func TestAddWalletInputNotEnoughInputs(t *testing.T) {
 	mockInput.On("RequiredTxOut").Return(&wire.TxOut{})
 	defer mockInput.AssertExpectations(t)
 
+	sd := &input.SignDescriptor{
+		Output: &wire.TxOut{
+			Value: budget,
+		},
+	}
+	mockInput.On("SignDesc").Return(sd).Once()
+
 	// Create a pending input that requires 10k satoshis.
 	pi := &SweeperInput{
 		Input:  mockInput,
@@ -435,19 +482,83 @@ func TestAddWalletInputNotEnoughInputs(t *testing.T) {
 	// Initialize an input set with the pending input.
 	set := BudgetInputSet{inputs: []*SweeperInput{pi}}
 
-	// Add wallet inputs to the input set, which should give us an error as
-	// the wallet cannot cover the budget.
+	// Add wallet inputs to the input set, which should return no error
+	// although the wallet cannot cover the budget.
 	err := set.AddWalletInputs(wallet)
-	require.ErrorIs(t, err, ErrNotEnoughInputs)
+	require.NoError(t, err)
 
-	// Check that the budget set is reverted to its initial state.
-	require.Len(t, set.inputs, 1)
-	require.Equal(t, pi, set.inputs[0])
+	// Check that the budget set is updated.
+	require.Len(t, set.inputs, 2)
 }
 
-// TestAddWalletInputSuccess checks that when there are enough wallet utxos,
+// TestAddWalletInputsEmptyWalletSuccess checks that when the wallet is empty,
+// if there is a normal input, no error is returned.
+func TestAddWalletInputsEmptyWalletSuccess(t *testing.T) {
+	t.Parallel()
+
+	wallet := &MockWallet{}
+	defer wallet.AssertExpectations(t)
+
+	// Specify the min and max confs used in
+	// ListUnspentWitnessFromDefaultAccount.
+	minConf, maxConf := int32(1), int32(math.MaxInt32)
+
+	// Assume the desired budget is 10k satoshis.
+	const budget = 10_000
+
+	// Create a mock input that has required outputs.
+	mockInput1 := &input.MockInput{}
+	defer mockInput1.AssertExpectations(t)
+
+	mockInput1.On("RequiredTxOut").Return(&wire.TxOut{})
+
+	sd := &input.SignDescriptor{
+		Output: &wire.TxOut{
+			Value: budget,
+		},
+	}
+	mockInput1.On("SignDesc").Return(sd).Once()
+
+	// Create a pending input that requires 10k satoshis.
+	pi1 := &SweeperInput{
+		Input:  mockInput1,
+		params: Params{Budget: budget},
+	}
+
+	// Create a mock input that doesn't require outputs.
+	mockInput2 := &input.MockInput{}
+	defer mockInput2.AssertExpectations(t)
+
+	mockInput2.On("RequiredTxOut").Return(nil)
+	sd2 := &input.SignDescriptor{
+		Output: &wire.TxOut{
+			Value: budget,
+		},
+	}
+	mockInput2.On("SignDesc").Return(sd2).Once()
+
+	// Create a pending input that requires 10k satoshis.
+	pi2 := &SweeperInput{
+		Input:  mockInput2,
+		params: Params{Budget: budget},
+	}
+
+	// Mock the wallet to return empty utxos.
+	wallet.On("ListUnspentWitnessFromDefaultAccount",
+		minConf, maxConf).Return([]*lnwallet.Utxo{}, nil).Once()
+
+	// Initialize an input set with the pending inputs.
+	set := BudgetInputSet{inputs: []*SweeperInput{pi1, pi2}}
+
+	// Add wallet inputs to the input set, which should return no error
+	// although the wallet is empty.
+	err := set.AddWalletInputs(wallet)
+	require.NoError(t, err)
+}
+
+// TestAddWalletInputsSuccess checks that when there are enough wallet utxos,
 // they are added to the input set.
-func TestAddWalletInputSuccess(t *testing.T) {
+func TestAddWalletInputsSuccess(t *testing.T) {
 	t.Parallel()
 
 	wallet := &MockWallet{}